The present invention pertains to the technical field of steering systems for vehicles, and in particular to techniques for reducing torque steering in a vehicle.
In recent years, as engine performance has improved, the output torque of the engine has also increased. When the output torque of the engine increases, even a small difference between the left/right tilt angles can lead to a significant difference between the left/right driving torques, so that torque steering takes place.
Japanese Kokai Patent Application No. 2004-9843 shows a torque steering suppressing structure of a vehicle. On the side of the left/right wheel with a longer distance from the differential gear, an intermediate shaft connected to the differential gear and the drive shaft is set so that the tilt angles (namely, joint bending angles) of the left/right drive shafts are the same, and the lengths of the left/right drive shafts are also equal. To obtain the same tilt angle for the left/right drive shafts, it may be necessary to use support bracket to fix the intermediate shaft, and these may protrude significantly outward from the vehicle lateral direction center.
Japanese Kokai Patent Application No. Hei 9 [1997]-207802 shows a technology for reducing the torque steering by driving an electric motor to cancel the torque steering in a vehicle carrying an electric power-assisting steering system. This technology may require additional components such as an electric motor. There may be waste in output upon starting. Also, when generation of torque steering takes place in large vehicles carrying high power engines, an electric power steering system, which has a smaller assisting force than that of a hydraulic power steering system, may be difficult to adapt to this application.